Sgreen-scraper for pulp or paper mills



(No Model.)

M. V. STREETER.

SCREEN SGRAPER FOR PULP OR'PAPER MILLS.

No. 883,026. Patented May 15, 1888.

lJNrrED STATES i ATENT rrrcn.

$CREEN==SCRAPER FOR PULP OR PAPER MILLS.

SPECIFICATION forming part of Letters Patent No. 383,026, dated May 15,1868.

Application filed June 25, 1887. Serial No. 242,449. (No model.)

To all whom it may concern.-

Be it known that I, MARTIN V. STREETER, a citizen of the United States,residing at Franklin Falls, in the county of Merrimac and State of NewHampshire, have invented certain new and useful Improvements inScreen-Scrapers for Pulp or Paper Mills, of which the following is aspecification.

The object of this invention is to provide mechanism, in connection withan ordinary pnlp-screen,which shall carry out all chips and smallparticles which will not dissolve or cannot be converted into pulp; andtheinvention consists of the improved devices combined and arranged ashereinafter described, and pointed outin the appended c1aims,and clearlyillustrated in the accompanying drawings,

forming a part of this specification, of which- Figure 1 represents alongitudinal sectional view of a screen to which my improvements areapplied, Fig. 2 being a general plan of same; Fig. 3, an enlargedsectional view in perspective of one of the scrapers and its chain belt;and Fig. 4 represents said scraper in cross-section, the chain belt insection, and a portion of-the sprocket-wheel for carrying the same, allin their relative position.

Similar letters designate corresponding parts.

A is the rat or screen-frame,which, to serve my purpose, is preferablyprovided with inclined or curved ends A, as seen best in Fig. 1. Thesemay be composed of wood or metal, as found most desirable. Between thesecurved ends the ordinary screen bottom may be placed, formed of slottedplates or segments 13, their slots 1) running lengthwise orlongitudinally with the said screen-frame. These plates are secured byscrews 1) in the usual way to crossbars 0, connecting the vertical sidesof said screen-frame A.

Near each end and upon the vertical sides of said screenframe aresecured bearings D, in which are mounted shafts E, which carry betweensaid bearings pulleys F. For ascreen of ordinary size but two of thesepulleys are required for each shaft; but others maybe added, if desired.Chain belts G connect one set with the other, and those pulleys whichare mounted upon the shaft carrying the drivepulley P (which in thedrawings is shown at the right side) are of the form known as I sprocketor rag wheels, the projections f, which carry the chains, being shown inFigs.

1 and 4t.

Scrapers H, which are preferably cast in the form of channel-iron, aresecured at regular intervals to the chains G, the connection beingconveniently made by means of a bridge, 9, joining the sides of a link,9, and adapted to be sunk and secured by a screw, I, within the groove7b of the said scraper H, near each end thereof. These scrapers are heldto their work by their own weight, this being permitted by reason of theslack in the chains G, the upper portions of which are maintained in ahorizontal position by means of the supports or slideways J, (sustainedat their proper heights by the bars 3",) upon which the scrapers H restwhile being moved from one to another set of pulley-wheels F in thedirection of the arrows above Fig. 1, thus allowing the scrapers on theunder sides of the chains G to slide along the screen-bottom B, (channelside down,) carrying all chips or waste matter which will not passthrough said screen before them to the incline A (shown best in Fig. 1,)where they pass into a proper receptacle.

There are several advantages in using slack chains for carrying thescrapers, among which may be mentioned the following-to wit: thescrapers are thereby enabled to follow each other along the screen anddo their work, even though the said screen may have become uneven orirregular from any cause, or through accident some heavy object may havedropped into the screen, in which event, if said object is too heavy tobe carried out by the scrapers, they willsuccessively ride over it andcontinue to do their work to a certain extent until the difficulty bediscovered by a watch man-a screen-tender; and, finally, I may add, thisconstruction combines simplicity and economy.

I am aware that screen-scraping devices have been previously patented.Some ofthese employ rotary brushes driven by rack and pinion; or thebrushes are attached to a leather belt which is passed taut overordinary beltpullcys. These, however, are continually wearing off, andas there is no means for insuring cont-act of the brushes and screenbetween the pulleys, said screen may never be thoroughly freed from therefuse matter which the brushes are designed to carry off. Thisdifficulty is entirely avoided by using slack belts, (which mustnecessarily be in the form of chain belts) having metallic or otherheavy scrapers attached,and also in providing means supporting the upperscrapers so that the lower ones may drop of their own weight and restupon the screen while being moved across the same. Thus it is obviousthat to use taut .,.belts, or even chains, would defeat the objectsuitable scrapers arranged at regular intervals and carried thereon, andsuitable slideways for carrying the upper scrapers at a uniform heightfrom one to another set of sprocket-wheels, for the purpose set forth.

2. The combination of a screen having inclined ends, a shaft andsprocket or rag wheels mounted on top near each end, two or more slackchains, suitable scrapers channeled on one side and arranged at regularintervals and carried thereon, and suitable slideways for carrying theupperscrapers at a uniform height from end to end of said screen,substantially for the purpose described.

In testimony whereofI affix my signature in presence of two witnesses.

. MARTIN V. STREETER.

\Vitnesses:

J. B. THURSTON, J. H. ALBIN.

